Ciguatera Toxin Poisoning

From the office of the Medical Health Officer

Ciguatera toxin poisoning after eating locally-bought rock cod

Food poisoning symptoms plus weakness, tingling, or temperature sensation reversal - CONSIDER CIGUATERA FISH POISONING. Ask that uneaten food be saved and call Public Health.

If you see patient(s) with symptoms of:

• vomiting, cramps, and/or diarrhea with myalgia, arthralgia, pruritis, aching teeth, malaise, or headache
• neurological symptoms such as dry mouth, perioral/throat paresthesia, metallic taste, paresthesia/tingling of extremeties, blurred vision, photophobia, and transient blindness. Severe cases may have temperature sensation reversal (hot things feel cold; cold things evoke an electric/burning sensation), bradycardia, hypotension, cranial nerve palsies, flaccid paralysis, and respiratory paralysis.

then think of ciguatera fish poisoning, even in people who have not traveled.

A Surrey physician picked up ciguatera poisoning this month in three people who had eaten locally-purchased imported rock cod, also sometimes referred to as “ling cod” or “kawa kawa.”

Ciguatera poisoning is caused by an accumulation of marine biotoxins in fish from dinoflagellates found mainly in tropical waters. Large carnivorous tropical fish (such as barracuda and red snapper) at the top of the food chain accumulate higher concentrations of ciguatera toxins and thus pose the highest risk. Any part of an affected fish may contain the ciguatera toxin, but the liver, head, gonads and viscera have been reported to contain higher concentrations. It is impossible for the consumer to distinguish between toxic and non-toxic fish because the colour as well as the external and internal appearance of the fish are similar. Cooking or freezing the fish does not affect the toxins.

Symptoms usually appear 1 to 12 hours after consumption and can persist from days to several months. The diagnosis is based on clinical presentation and is confirmed by detecting ciguatera toxin in a sample of the fish that was eaten. Treatment is predominantly supportive ^{1, 2} . IV fluids are given to replace GI losses. Atropine is indicated for bradycardia and temporary electrical pacing may be required in patients with refractory symptoms. Severe hypotension may require use of pressors. Although mannitol is often recommended to reduce duration of neurologic symptoms, the only double-blind trial failed to show benefit.³

Ciguatera poisoning in Canada is likely both under-diagnosed and under-reported. Most cases in Canada involved people who ate fish in the Caribbean while on vacation, but a few cases have also been reported from eating imported tropical fish. Ciguatera poisoning is increasingly likely to occur in those with no travel history to endemic areas but who have eaten imported tropical fish from a restaurant or fish store. Since the first report in 1983, it has been estimated that such events occur in Canada approximately every 10 months.⁴
Tropical fish and products made from them should be purchased from only known, reputable retail outlets. Seasoned fisherman in the tropics rub fish organs on their gums; if tingling results, the fish is not safe to eat.⁵

References:

1. Perkins RA, Morgan SS. Poisoning, Envenomation, and Trauma from Marine Creatures. Am Fam Phys 69(4) 2004
2. Hung Y-M et al. Persistent bradycardia caused by ciguatoxin poisoning after barracuda fish eggs ingestion in southern Taiwan. Am J Trop Med Hyg, 73(6), 2005,1026-027
3. Schnorf H et al. A double-blind randomized trial of mannitol therapy. Neurology 2002;58:873-880
4. Ciguatera food poisoning linked to the consumption of imported barracuda – Montreal, Quebec, 1998 CCDR 26(09) 1 May 2000
5. Caplan CE. Ciguatera fish poisoning CMAJ 1998 159: 1394.